Search system and search method

Abstract

To provide a search system and search method capable of accurately and quickly determining the location of search targets such as animals, people, and objects.SOLUTION: The search system includes first devices 1 installed at a plurality of objects whose locations can be identified (e.g., utility poles 7), or first devices 1 mounted at arbitrary positions and capable of acquiring its own location information, and a second device 2 mounted on or associated with a search target 6. The search system includes distance calculation means for calculating the distance between each of the plurality of the first devices 1 and the second device 2 on the basis of the propagation time of information or signals between each of the plurality of first devices 1 and the second device 2 and position determination means for determining the location of the search target 6 on which the second device 2 is mounted on the basis of the distances between each of the plurality of first devices 1, as calculated by distance calculation means, and the second device 2 and on the location information of the objects to which the first devices 1 are mounted (e.g., utility poles 7), or the mounted portion of the first devices, or the self- location information obtained by the first devices 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a search system and a search method capable of specifying the position of a search target such as an animal, a person, or an article that requires searching.

Background Art

[0002] There have been quite a few cases where animals kept in gardens, schools, homes, etc. go missing and pose a threat to public safety. In addition, vehicles, high-class furniture, etc. may be victims of theft, or the whereabouts of specific persons (such as dementia patients or criminals) may become unknown. It is also a social demand to be able to specify the position of the animal, person, or article to be searched for at an early stage.

[0003] Conventionally, for example, when a kept animal goes missing, posters are put up on utility poles, bulletin boards, etc., or information about the kept animal is published in town magazines, and then waiting for contact from the person who found it. In addition, when a kept animal goes missing, or when it becomes separated from its owner due to a disaster or an accident, etc., in order to identify the owner, it is obligatory to attach a microchip to the kept animal (see Non-Patent Document 1).

[0004] In addition, when a vehicle, high-class furniture, etc. are stolen, or when the whereabouts of a specific person becomes unknown, a report of theft or a report of a missing person is submitted to deal with it.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, posting on posters or town magazines, or filing a lost property report or a missing person report do not actively search for the object to be searched. Therefore, it takes time until the object to be searched is found (until the position of the object to be searched is specified), and the probability of finding the object to be searched cannot be said to be high.

[0007] In addition, current microchips attached to domestic animals do not have the function of transmitting their own information, and are used by reading the information of the microchip via an external reader and comparing the read information with the data in the database. Therefore, they are only used as solid identification cards, and the position information and displacement information of the microchip cannot be grasped.

[0008] The present invention has been made in view of such circumstances, and the main problem is to provide a search system and a search method capable of accurately and promptly specifying the position of an object to be searched, such as an animal, a person, or an article.

Means for Solving the Problem

[0009] In order to achieve the above problems, a search system according to the present invention is a search system for specifying the position of an object to be searched by using a first device attached to a plurality of objects whose position information can be specified and a second device attached to or associated with the object to be searched, distance calculation means for calculating the distance between each of the plurality of first devices and the second device based on the propagation time of information or signals between each of the plurality of first devices and the second device; position specifying means for specifying the position of the object to be searched on which the second device is mounted based on the distances between each of the plurality of first devices and the second device calculated by the distance calculation means and the position information of the object on which the first device is mounted or the mounting site of the first device; and is characterized by having the above.

[0010] Here, the object to be searched is not particularly limited, and it may be an animal (including pets) raised in a garden, school, home, etc., a specific person (a person with a disability such as a dementia patient or a protected person such as a criminal), or an item (a vehicle, household goods, a work of art, an antique, a portable item, etc.), as long as it is an object to which the first device can be attached or associated.

[0011] Attaching to the object to be searched does not mean only directly attaching to the surface of the object to be searched, but also includes fixing to an object that covers the object to be searched or an object attached to the object to be searched. In addition, it includes not only the case of fixing with a string, band, wire, chain, adhesive, etc. outside the object to be searched, but also the mode of embedding inside.

[0012] Associating with the object to be searched means placing the second device in a state of moving together with the object to be searched even if it is not attached to the object to be searched. For example, when the object to be searched is a vehicle or a bag, it includes the state of putting it inside the vehicle or the bag.

[0013] In addition, a plurality of objects (objects to which the first device can be attached) whose position information can be specified may be targeted for which the position information is stored in a database and managed, such as utility poles, towers, roadside devices, structures such as offices, buildings, and architectures. In particular, in an area with few buildings, structures such as utility poles and towers may be the attachment targets of the first device. Also, in an area with few utility poles or where the trend of poleless progress is advancing, structures such as roadside devices and buildings such as buildings may be the attachment targets of the first device, and appropriate selection may be made according to the search area.

[0014] In addition, the position information of the object to which the first device is attached or the attachment site of the first device may be two-dimensional position information specified by coordinates such as latitude and longitude, but it is preferably three-dimensional position information including height information (ellipsoidal height, elevation, etc.). Even when the first device is attached to a utility pole, a building, etc., the height of the installation location of the utility pole or building varies depending on the location, and the height of the first device attached to the utility pole or building from the ground surface also varies. By managing the height position of the first device, it becomes possible to more accurately specify the position information (three-dimensional position information) including the height of the second device.

[0015] For example, by making the attachment height of the first device different for each utility pole or building, managing the attachment height of the first device for each utility pole or building, and using the three-dimensional position information, it becomes possible to grasp the three-dimensional position information of the second device. By acquiring the three-dimensional position information of the second device in this way, it becomes possible to grasp the position information of a vehicle in a multi-story parking lot, an animal on the rooftop of a building, or an article in a building.

[0016] Therefore, the distance calculating means calculates the distance between each of the plurality of first devices and the second device attached to or associated with the object to be searched, and the position specifying means determines the distance between each of the plurality of first devices and the second device, and based on the position information of the object to which the first device is attached or the position information of the attachment site of the first device, it becomes possible to specify the position of the second device, that is, the position of the object to be searched.

[0017] The calculation of the distance between the first device and the second device by the distance calculation means is premised on the first device and the second device being within a range where they can mutually transmit and receive information or signals. Therefore, if the first device and the second device are too far apart, the distance between them cannot be calculated. However, if the search target to which the second device is attached is displaced and there is a first device with which information or signals can be mutually transmitted and received, the distance between the first device and the second device is calculated by the distance calculation means therebetween. And if there are three or more (more preferably, four or more) first devices for which distance calculation is possible, the position of the second device can be specified by the position specifying means (if there are four or more, height information can also be grasped). Therefore, by adjusting the object to which the first device is attached or the mounting height and appropriately dispersing the first devices, the position of the displaced second device can be surely captured.

[0018] In order to specify the position of the second device, in addition to the distance between each of the plurality of first devices and the second device, the position information of each of the first devices is required. In the above-described configuration, the position information of the object to which the first device is attached or the position information of the attachment site of the first device is used. However, if the first device has a GPS function, an altitude measurement function, etc. and can acquire its own position information (preferably, three-dimensional position information), that position information may be used.

[0019] That is, the search system according to the present invention is a search system that uses a first device attached at an arbitrary plurality of locations and capable of acquiring its own position information, and a second device attached to or associated with the search target to specify the position of the search target, distance calculation means for calculating the distance between each of the plurality of first devices and the second device based on the propagation time of information or signals between each of the plurality of first devices and the second device; position specifying means for specifying the position of the search target to which the second device is attached based on the distance between each of the plurality of first devices and the second device calculated by the distance calculation means and the position information of itself acquired by the first device; may be configured to have.

[0020] Here, the first device capable of acquiring its own position information is one that has a GPS function, an altitude measurement function, etc. in the first device to acquire its own position information (preferably, three-dimensional position information). By using such a first device, the object to which it is attached does not need to be an object whose position information can be specified, and it can be attached to any location (such as the side of the road, a tree in a park, a pile driven into the ground, etc.), so it becomes easier to adjust the arrangement of the first device.

[0021] Note that if the above-described distance calculation means can calculate without deliberately synchronizing the clock of the first device and the clock of the second device, there is no need to deliberately synchronize them. Therefore, even if the distance is calculated on the premise of the time difference (time offset) between the time of the clock of each first device and the time of the clock of the second device, it may be acceptable.

[0022] That is, the propagation time of information or a signal between each of a plurality of first devices and the second device is calculated based on the difference between the time of the clock of the first device when the information or signal is transmitted from the first device and the time of the clock of the second device when the information or signal transmitted from the first device is received by the second device, and the difference between the time of the clock of the second device when the information or signal is transmitted from the second device and the time of the clock of the first device when the information or signal transmitted from the second device is received by the first device. Thus, regardless of the presence or absence of the time difference between the clock of the first device and the clock of the second device, the distance between the first device and the second device can be calculated.

Advantages of the Invention

[0023] As described above, according to the search system and search method of the present invention, based on the propagation time of information or signals between each of the plurality of first devices and the second device, the distance between each of the plurality of first devices and the second device is calculated, and based on the calculated distance between each of the plurality of first devices and the second device, and the position information of the object to which the first device is attached, or the position information of itself acquired by the first device, the position of the search target to which the second device is attached or associated is specified. Therefore, if the second device is pre-mounted on the search target such as an animal, a person, an article, etc., even if they are missing or stolen, the position of the search target can be accurately and quickly specified.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 10

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.

[0026] In FIG. 1, the search system S is configured to include a plurality of first devices 1 and a second device 2 pre-mounted on the object to be searched 6. Further, this system may include a server device 3, an administrator terminal 4, and a communication network 5.

[0027] The first device 1 and the second device 2 can be directly communicatively connected. Also, the first device 1 can be connected to the server device 3 or the administrator terminal 4 via the communication network 5, and the second device 2 can also be connected to the server device 3 or the administrator terminal 4 via the communication network 5.

[0028] The first device 1 can be a device serving as a reference for synchronizing the clock of the second device 2. However, in this system, it is not always necessary to synchronize the clock of the first device 1 and the clock of the second device 2. Therefore, in the following example, the distance between the first device 1 and the second device 2 is calculated on the premise that there is a time difference between the clock of the first device 1 and the clock of the second device 2 without synchronizing the clock of the first device 1 and the clock of the second device 2, and the case of specifying the position of the second device 2 will be described.

[0029] Also, the first device 1 can function as the first device with respect to a plurality of second devices 2. When there are a plurality of second devices 2, each of these plurality of second devices 2 may be made to function as the first device with respect to a plurality of other second devices. That is, if the position of any one of the second devices can be specified as described later, it can be used to specify the position of other second devices by calculating the distance between that second device and other second devices.

[0030] As shown in FIG. 2, the first device 1 includes a control unit 11, an RF chip 12, and an oscillator 13.

[0031] The control unit 11 is composed of a CPU and a ROM, executes the program stored in the ROM, and controls the first device 1. The RF chip 12 is equipped with at least a clock 14, and may also be equipped with a phase detector. In addition, the RF chip 12 has a function of processing the transmission and reception of wireless signals, and the data received by the RF chip 12 is subject to arithmetic processing by the control unit 11.

[0032] The oscillator 13 oscillates at a predetermined frequency and outputs a signal for giving the operation timing of each part of the device. As the oscillator 13, a crystal oscillator or an atomic oscillator can be used. The clock 14 clocks based on the output signal of the oscillator 13 and outputs the time. The time clocked by the clock 14 is controlled by the control unit 11 to be transmitted to the second device 2 via the RF chip 12. When a phase detector is further provided, the phase of the carrier wave constituting the information received from the second device 2 is detected, and the phase of the signal transmitted by the oscillator 13 of the first device 1 is detected.

[0033] In this system, the installation location of the first device 1 is not particularly limited, but it is preferably installed in a building, structure, or building where the location information can be specified.

[0034] For example, in an area with few buildings, structures such as utility poles and towers that are provided at wide intervals can be used as the attachment target of the first device. Also, in an area with few utility poles or where the poleless trend is advancing, buildings such as buildings can be used as the attachment target of the first device, and it is advisable to select appropriately according to the search area of the target to be searched.

[0035] In addition, in this embodiment, in order to cover a wide area, for example, the case of attaching to an erected body such as a utility pole or a tower that supports overhead wires will be described. Utility poles and towers are scattered at predetermined intervals over a wide area, and various information including their location information is stored in a database and managed, so it is easy to specify the location information. Also, it is possible to install the first device 1 at a high place where the signal can easily reach a distant place.

[0036] Also, even when the first device is attached to a utility pole, the installation height of the first device may be made different for each utility pole, and the installation height of the first device may be managed for each utility pole together with the position information of the utility pole, and used as the position information (three-dimensional position information) of the attachment site of the first device.

[0037] Note that the position information of the installation location of the first device 1 may be stored in a server device 3 or the like in association with the identification information that can identify the first device 1, or may be obtained from another management server that manages the position information via the communication network 5.

[0038] Next, the second device 2 will be described. This second device 2 is pre-mounted on the object to be searched 6. That is, it is mounted on the object to be searched 6 in advance in case the object to be searched 6 becomes missing, stolen, or lost in the future before it becomes the object of search.

[0039] Here, the object to be searched 6 is not particularly limited, and includes animals (including pets) 6a raised in gardens, schools, homes, etc., people 6b such as disabled persons and probationers, articles such as vehicles 6c and art and crafts 6d, etc., and anything that the second device 2 can be attached to or associated with.

[0040] The second device 2 being attachable includes not only the case where the second device 2 is directly attached to the object to be searched 6 by some means, but also the case where it is fixed to something that covers or is attached to the object to be searched 6. Also, the second device 2 includes not only the case where it is fixed to the outside of the object to be searched 6 with a string, band, wire, chain, adhesive, etc., but also the mode of being embedded inside.

[0041] Therefore, if the object to be searched 6 is, for example, an animal (pet) 6a, in addition to the case where the second device 2 is attached to a wearable such as a collar, if the second device 2 is small enough to be microchipped, the mode of embedding it in the animal is also included.

[0042] In addition, the ability to accompany the second device 2 means that even when the object to be searched is not attached to the object to be searched, the second device is placed in a state of being moved together with the object to be searched. For example, when the object to be searched is a vehicle or a bag, it includes a state of putting it in the vehicle or the bag.

[0043] As shown in FIG. 3, the second device 2 includes a control unit 21, an RF chip 22, and an oscillator 23, each of which is connected by a bus. Further, it includes a RAM 24 and a storage unit 25, each of which is connected to the control unit 21 by a bus.

[0044] The RF chip 22 includes at least a clock 26, and may be configured to include a phase detector as needed.

[0045] The control unit 21 is configured to have a CPU and a ROM, executes a program stored in the storage unit 25, and controls the second device 2. The RAM 24 is a work area of the control unit 21, and the storage unit 25 is a storage area for storing programs and data. The control unit 21 performs arithmetic processing based on the programs and data read from the RAM 24 and the storage unit 25, and the data input from an input unit (not shown).

[0046] The RF chip 22 can transmit and receive data with other computer devices. The data received by the RF chip 22 is loaded into the RAM 24 and becomes the object of arithmetic processing by the control unit 21.

[0047] The oscillator 23 oscillates at a predetermined frequency and outputs a signal for giving the operation timing of each part of the device. As the oscillator 23, a crystal oscillator or an atomic oscillator can be used. The clock 26 keeps time using the output signal of the oscillator 23 as the reference clock and outputs the time. The time kept by the clock is controlled to be transmitted to the first device 1 via the RF chip 22 by the control unit 21. When it has a phase detector, it detects the phase of the carrier wave constituting the information received from the first device 1, and also detects the phase of the signal oscillated by the oscillator 23 of the second device 2.

[0048] Next, the server device 3 of the present invention will be described. The server device 3 can acquire the position information from the second device 2. Further, the acquired position information can be transmitted to the administrator terminal 4.

[0049] The acquired position information is stored as the position information of the search target 6 (second device 2) in the server device 3 or the administrator terminal 4. The position information of the search target 6 (second device 2) is transmitted to the server device 3, for example, from the second device 2, in association with the identification information that can identify the second device 2 and the time when the position information is specified. Note that the server device 3 may be capable of communicating between the first device 1 and the second device 2 via a smart meter installed in a building such as a building.

[0050] FIG. 4 is a block diagram showing the configuration of the server device 3 according to an embodiment of the present invention. The server device 3 includes at least a control unit 31, a RAM 32, a storage unit 33, and a communication interface 34, which are connected by an internal bus.

[0051] The control unit 31 is composed of a CPU, a ROM, etc., executes a program stored in the storage unit 33, and controls the server device 3. Further, the control unit 31 includes an internal timer for measuring time. The RAM 32 is a work area of the control unit 31. The storage unit 33 is a storage area for storing programs and data. The control unit 31 reads the program and data from the storage unit 33 and the RAM 32, and performs execution processing of the program based on information received from the first device 1 or the second device 2.

[0052] The administrator terminal 4 is a terminal used by an administrator to manage various information of the search target 6 that has received a search request. The administrator terminal 4 may manage one search target 6 or a plurality of search targets 6. Here, the management of various information of the search target 6 includes a process of confirming the position of the search target 6 and notifying the search requester of the information.

[0053] Specifically, the administrator terminal 4 receives the position information of the second device 2 (the object to be searched 6), and by associating the position information with the map information, the position of the object to be searched 6 can be displayed on the map on the display screen of the administrator terminal 4. At this time, the position information of the second device 2 (the object to be searched 6) may be received at predetermined time intervals as latitude and longitude information or coordinate positions in the XYZ coordinate system (see FIG. 5), and its history (the movement trajectory of the object to be searched 6) may be displayed on the map.

[0054] Note that the administrator terminal 4 has the same configuration as the server device 3. For example, it includes a control unit 41, a RAM 42, a storage unit 43, a communication interface 44, an input unit and a display unit (not shown), and each is connected by an internal bus (see FIG. 4).

[0055] (Distance calculation process) Next, using the above configuration, the process of calculating the distance between the first device 1 and the second device 2 will be described.

[0056] This distance calculation process is a process of calculating the distance between each of the first device 1 and the second device 2 based on the propagation time Tp of the information or signal between each of the first device 1 and the second device 2 when the first device 1 and the second device 2 are within the range of a distance where they can mutually transmit and receive information or signals.

[0057] The distance calculation process is executed at predetermined time intervals (for example, every minute) or every time a predetermined condition is satisfied, and the processes of steps S1 to S16 as shown in FIG. 6 are performed. Here, for the sake of convenience, the case of calculating the distance between one first device 1 and the second device 2 will be described.

[0058] First, information or a signal is transmitted from the first device 1 to the second device 2 (step S1). The information or signal transmitted from the first device 1 to the second device 2 is not particularly limited.

[0059] In the first device 1, the time (T11) when the information or signal is transmitted in step S1 is recorded (step S2), and the recorded time is stored in the memory in the control unit 11 (step S3).

[0060] Thereafter, in response to this, the second device 2 receives the information or signal from the first device 1 (step S4). In the second device 2, the time (T21) when the information or signal is received in step S4 is recorded (step S5). Then, the recorded time (including the measured phase if the phase is measured) is stored in the memory in the control unit 21 or the storage unit 25 (step S6).

[0061] Next, the second device 2 transmits information or a signal to the first device 1 (step S7). The information or signal transmitted from the second device 2 to the first device 1 is not particularly limited. In the second device 2, the time (T22) when the information or signal is transmitted in step S7 is recorded (step S8). Then, the recorded time is stored in the memory in the control unit 21 or the storage unit 25 (step S9).

[0062] The first device 1 receives the information or signal transmitted in step S7 (step S10). In the first device 1, the time (T12) when the information or the signal is received in step S10 is recorded (step S11). Then, the recorded time (including the measured phase if the phase is measured) is stored in the memory in the control unit 11 (step S12).

[0063] Thereafter, the first device 1 transmits the information regarding the time (T11) when the signal was transmitted in step S1, which was stored in step S3, and the information regarding the time (T12) when the signal was received in step S10, which was stored in step S12, to the second device 2 via the RF chip 12 of the first device 1 (step S13). At this time, if the position information of the utility pole 7 to which the first device 1 is attached is recorded, it is transmitted to the second device 2 together with the position information.

[0064] Then, in the second device 2, information regarding the time (T11) when the first device 1 transmits information or a signal in step S1 and information regarding the time (T12) when the first device receives information or a signal in step 10 are received (step S14).

[0065] Next, the second device 2 calculates the distance between the first device 1 and the second device 2 (step 15). This distance calculation is performed as follows.

[0066] After the information regarding the time (T11) of the clock of the first device is carried on a radio wave and sent to the second device 2, the difference between the time (T21) of the clock of the second device 2 when this information is received by the second device 2 is recorded as ΔTa on the second device side. That is, the time of the clock of the first device when the first device 1 transmits information or a signal to the second device 2 is defined as T11, the time of the clock of the second device when the information or signal transmitted from the first device 1 is received by the second device 2 is defined as T21, and if the difference is ΔTa, this ΔTa is the sum of the time difference (time difference: T20 - T10) between the clocks of the first device 1 and the second device 2 and the propagation delay (propagation time) Tp, so the relationship of Equation 1 holds. This time difference (T20 - T10) becomes zero if the clocks of the first device and the second device are synchronized, but here it is assumed that there is a time difference (not synchronized). [Equation 1] ΔTa = T21 - T11 = (T20 - T10) + Tp

[0067] To obtain this propagation time Tp, information regarding the time of this clock (T22) is also sent from the second device 2 to the first device 1, and the difference from the time of the clock of the first device 1 (T12) when received by the first device 1 is recorded as ΔTb on the first device side. That is, the time of the clock of the second device when transmitting information or a signal from the second device 2 to the first device 1 is defined as T22, and the time of the clock of the first device 1 when the information or signal is transmitted from the second device 2 and received and timed by the first device 1 is defined as T12. If the difference is ΔTb, this ΔTb is the sum of the time difference (time offset: T10 - T20) between the clock of the first device 1 and the clock of the second device 2 and the propagation delay (propagation time) Tp, so the relationship of Equation 2 is obtained. Here too, the time difference (T10 - T20) becomes zero if the clocks of the first device 1 and the second device 2 are synchronized. However, here it is assumed that there is a time difference (not synchronized) (T10 - T20). [Equation 2] ΔTb = T12 − T22 = (T10 - T20) + Tp

[0068] Since the time differences (T20 - T10) and (T10 - T20) between the times of the respective clocks are added by this time difference amount when transmitting from the first device to the second device, and are subtracted by the same amount of time difference when transmitting from the second device to the first device, in order to obtain the propagation time Tp, when taking the sum of Equation 1 and Equation 2, the terms of the time differences (T20 - T10) and (T10 - T20) are canceled out, resulting in the relationship of Equation 3. [Equation 3] Tp = (ΔTa + ΔTb) / 2 = ((T21 - T11) + (T12 − T22)) / 2

[0069] Incidentally, the time difference (T10 - T20) has the relationship of Equation 4 according to [Equation 1] - [Equation 2]. [Equation 4] (T10 - T20) = (ΔTa − ΔTb) / 2

[0070] Therefore, the propagation time Tp can be calculated based only on the time read by the clock of the first device 1 and the time read by the clock of the second device 2.

[0071] Thereafter, the separation distance between the first device 1 and the second device 2 is calculated by multiplying the propagation time calculated by Equation 3 by the propagation speed (e.g., high speed) of the information or signal.

[0072] Then, the separation distance between the first device 1 and the second device 2 calculated in step S15 is stored in the memory or storage unit 25 in the control unit 21 (step S16). By executing this step 16, the distance calculation process ends.

[0073] Therefore, in Equation (3), since the term of the time deviation (time difference: T20 - T10) between the clock of the first device 1 and the clock of the second device 2 is not included, regardless of the presence or absence of the time difference between the clock of the first device 1 and the clock of the second device 2, the propagation time during which information or a signal propagates between the first device 1 and the second device 2 can be calculated.

[0074] The above distance calculation process can be performed between all the first devices 1 within the range of the distance at which information or a signal can be transmitted and received with the second device 2. Therefore, when the second device 2 (the object to be searched 6) moves and its position changes moment by moment, the distance calculation process is performed only between the first device 1 and the second device 2 within the range of the distance at which information or a signal can be transmitted and received at the time when this process is started. Therefore, the first device that is the calculation target of the distance from the second device 2 will change over time.

[0075] In the above, even if there is a time difference between the clock of the first device 1 and the clock of the second device 2, it is possible to calculate the distance between the first device and the second device. Therefore, it is not necessary to deliberately synchronize the clock of the first device 1 and the clock of the second device 2. However, based on the time difference calculated by Equation 4, the time in the first device 1 or the second device 2 may be corrected (synchronize the time of the clock of the first device 1 and the time of the clock of the second device 2), and then the propagation time may be calculated to calculate the distance.

[0076] [Position identification process] Next, the process of identifying the position of the search target 6 with the second device 2 attached will be described. This position identification process is a process of identifying the position of the second device 2 based on the distances between each of the plurality of first devices 1 and the second device 2 calculated in the distance calculation process. Since the second device 2 is provided in the search target 6, it can be said that this is a process of identifying the position of the search target 6.

[0077] It is desirable that this position identification process be performed immediately after the distance calculation process is completed. Also, in order to identify the position of the second device 2, it is assumed that in the distance calculation device, the distances between each of the plurality of first devices 1 and one second device 2 have been calculated.

[0078] That is, when one second device 2 and the plurality of first devices 1 are at the same height position (exist on the same XY plane), based on the distances between one second device 2 and at least three first devices 1 and the position information of each of the three first devices 1 used for calculating this distance, it becomes possible to identify the position of the second device 2.

[0079] Also, when one second device 2 and the plurality of first devices 1 are not on the same plane, based on the distances between one second device 2 and each of the four first devices 1 and the position information of each of the four first devices 1 used for calculating this distance, it becomes possible to identify the position of the second device 2.

[0080] Note that even when the height of one second device 2 is different from that of any of the plurality of first devices 1, if the distances between one second device 2 and each of the three first devices 1 are known, it is possible to identify the approximate position of the second device 2.

[0081] Therefore, in this system, if the number of data on the distances between the first device 1 and the second device 2 can be made three or more, the position of the second device 2 can be identified. So, even when the second device 2 moves, it is advisable to appropriately disperse and arrange the first devices so that the second device 2 can transmit and receive information or signals with at least three first devices.

[0082] In FIG. 7, a flowchart of the position identification process according to an embodiment of the present invention is shown. This position identification process can be executed by any one of the first device 1, the second device 2, or the server device 3. When the position identification process is executed by the first device 1 or the server device 3, the distance between each of the plurality of first devices 1 and the second device 2 and the position information of the first device 1 may be transmitted to and used by the first device 1 or the server device 3 in association with the identification information of the second device 2.

[0083] First, on the premise of executing this position identification process, it is necessary to be able to obtain at least the distance data between three different first devices and the second device at the same time or at a nearby time. Here, the nearby time is a time within a predetermined time range from a certain time. If it is not calculated at the same time or at a nearby time (for example, when the time measured for the propagation time of information or signals between each of the plurality of first devices 1 and the second device 2 is at the same time or at a nearby time), assuming that the second device 2 is moving, it becomes difficult to accurately identify its position.

[0084] Therefore, first, it is determined whether or not the number of distance data between the first device 1 and the second device 2 within a predetermined time range is three or more (step S21).

[0085] If the number of distance data between the first device 1 and the second device 2 within the predetermined time range cannot be obtained as three or more, this position identification process is not executed, and waiting is performed until three or more distance data are obtained within the predetermined time.

[0086] And when three or more distance data can be obtained within the predetermined time range, based on the distance between each of the plurality of first devices 1 and the second device 2 and the position information of the object to which the first device 1 is attached or the attachment site of the first device used for calculating this distance, the position of the second device, that is, the position of the search target on which the second device is mounted, is identified (step S22). Here, the position information of the first device 1 may be stored in advance in any one of the second device 2 that executes the position identification process, the first device 1, and the server device 3. Also, the calculation process for identifying the position of the second device 2 is not particularly limited.

[0087] The identified position of the second device 2 is associated with the time when the position was identified, the position information of the first device 1, the identification information of the second device 2, etc., and is stored in the memory in the control unit 11 of the first device 1, the memory in the control unit 21 of the second device 2, or the storage unit 33 of the server device 3 (step S23).

[0088] Then, the position information and movement trajectory of this second device 2 are notified to the requester who requested the search for the search target 6 in a method desired by the requester, such as an electronic mail or SNS registered in advance, together with the time when the position was identified, etc. (step S24).

[0089] The position identification process ends by the notification process of this step S24.

[0090] Therefore, if there are three or more (more preferably, four or more) first devices 1 capable of transmitting and receiving information or signals to and from the second device 2 attached to the search target 6 within a predetermined time range, the distances between each first device 1 and the second device 2 calculated by the distance calculation process at the same time or at nearby times, and the position information of the utility pole 7 to which each first device 1 used for this distance calculation is attached, or the position information of the attachment site of the first device 1, that is, the position information of the utility pole 7 to which the first device 1 is attached and the attachment height of the first device 1, based on these, the position of the second device 2 is identified by the position identification process. So, for example, as shown in FIG. 8, when the search target 6 equipped with the second device 2 moves from a position where the distance can be calculated with four first devices 1 as shown in (a) to a position where the distance can be calculated with three first devices 1 as shown in (b), it becomes possible to continuously or intermittently identify the position of the second device 2 over time. For this reason, it becomes possible to notify the search requester of the position information and movement trajectory of the search target 6 together with information such as the time when the position was identified.

[0091] In addition, by using three-dimensional position information that includes the height information (such as the height of the ellipsoid or elevation) of the first device, even when the first device 1 is attached to the utility pole 7, for example, the height of the installation location of the utility pole 7 varies from place to place, and the height from the ground surface of the first device 1 attached to the utility pole 7 also varies. Therefore, by managing the position of the attachment height of the first device 1, it becomes possible to more accurately specify the position (three-dimensional position) of the second device 2.

[0092] For example, by varying the attachment height of the first device for each utility pole and using the position information (three-dimensional position information) of the attachment site of the first device, it becomes possible to grasp the three-dimensional position information of the second device. Therefore, if the second device 2 is attached or associated with a stolen vehicle, it becomes possible to specify the position (floor number and parking area) of the stolen vehicle in a multi-story parking lot. Also, if the second device 2 is attached to a missing animal, it becomes possible to specify the position even if the animal is on the rooftop of a building. If the second device 2 is attached or associated with stolen goods, it also becomes possible to specify the location (floor number, storage location, etc.) of the stolen goods inside a building.

[0093] Note that in the above examples, as an example of an object for which the position information for attaching the first device 1 can be specified, an example of installing it on a fixed object (such as a utility pole, a tower, a building, etc.) that is permanently installed like a building or a structure is shown. However, as long as it is an object for which the position information can be specified, the first device 1 may be installed not only on a fixed object but also on a moving object.

[0094] For example, many vehicles are equipped with a navigation system and can specify the position of their own vehicle by means of GPS or the like. Also, the altitude positioning accuracy using GPS has been improving. Therefore, as shown in FIG. 9, if the first device 1 is attached to the vehicle 8 to make it a search vehicle, and information or signals can be transmitted and received between the first device 1 and the second device 2 attached to the object to be searched 6, the distance between the vehicle 8 and the object to be searched 6 can be calculated. If a total of three or more distances, including the distances between the first device 1 and the second device 2 attached to the nearby utility pole 7 and other vehicles 8, are calculated, it becomes possible to specify the position of the object to be searched 6.

[0095] In the above description, vehicle 8 is taken as an example of a moving object capable of specifying position information. However, the present invention is not limited thereto, and other moving objects such as ships, trains, drones (including aerial drones, water drones, and underwater drones) may also be applicable.

[0096] According to such a configuration, since the installation area of the first device 1 is not fixed, it is possible to perform a search while changing at any time the area where the search target 6 attached with the second device 2 is likely to exist.

[0097] In addition, in the above configuration, an example in which the first device 1 is attached to an object capable of specifying position information has been described. The reason for attaching the first device 1 to an object capable of specifying position information is that the position information of the first device 1 is required to specify the position of the second device 2.

[0098] Therefore, if the position information of the first device 1 can be acquired by the first device itself, the object to which the first device 1 is attached may be an object that cannot specify position information, and the first device 1 can be installed at an arbitrary location. That is, it is possible to specify the position of the search target 6 by using the first device that can be attached to any plurality of locations (three or more locations) and can acquire its own position information, and the second device attached to the search target.

[0099] In FIG. 10, a configuration example of the first device 1 capable of acquiring its own position information is shown. This first device 1, similar to FIG. 2, includes a control unit 11, an RF chip 12, and an oscillator 13, and further includes a GPS receiver 15 and an altimeter 16 as necessary. By capturing the signal received from the GPS satellite and detecting its own altitude, it can acquire its own three-dimensional position information.

[0100] In addition, since other configurations are the same as those of the first device 1 shown in FIG. 2, the same reference numerals are given to the same parts and the description thereof is omitted.

[0101] By using such a first device 1, the position information of the first device 1 can be obtained regardless of where the first device 1 is installed. Therefore, if the distance calculation means calculates the distance between each of a plurality (three or more) of the first devices 1 and the second device 2, based on the calculated distances and the position information of itself obtained by the first device 1, it becomes possible to specify the position of the search target 6 to which the second device 2 is attached.

Explanation of Signs

[0102] 1 First device 2 Second device 6 Search target 7 Utility pole 8 Vehicle S Search system

Claims

1. A search system for identifying the position of a search target by using a first device attached to a plurality of objects capable of identifying position information and a second device attached to or associated with the search target, distance calculation means for calculating the distance between each of the plurality of first devices and the second device based on the propagation time of information or signals between each of the plurality of first devices and the second device; position identification means for identifying the position of the search target to which the second device is attached based on the distances between each of the plurality of first devices and the second device calculated by the distance calculation means and the position information of the object to which the first device is attached or the attachment site of the first device; A search system, characterized by comprising the above.

2. A search system for identifying the position of a search target by using a first device attached at arbitrary multiple locations and capable of acquiring its own position information and a second device attached to or associated with the search target, distance calculation means for calculating the distance between each of the plurality of first devices and the second device based on the propagation time of information or signals between each of the plurality of first devices and the second device; position identification means for identifying the position of the search target to which the second device is attached based on the distances between each of the plurality of first devices and the second device calculated by the distance calculation means and the position information of itself acquired by the first device; A search system, characterized by comprising the above.

3. The search system according to claim 1, wherein the distance calculation means calculates the distance on the premise of the time difference between the time of the clock of each of the first devices and the clock of the second device.

4. the difference between the time of the clock of the first device when information or a signal is transmitted from the first device and the time of the clock of the second device when the information or signal transmitted from the first device is received by the second device; The difference between the time of the clock of the second device when information or a signal is transmitted from the second device and the time of the clock of the first device when the information or signal transmitted from the second device is received by the first device The search system according to claim 1, wherein the propagation time is calculated based on the difference.

5. The search system according to claim 1, wherein the plurality of objects whose position information can be specified are utility poles, towers, or moving bodies capable of acquiring their own position information.

6. A search method for specifying the position of a search target using a first device attached to a plurality of objects whose position information can be specified and a second device attached to or associated with the search target, A distance calculation step of calculating the distance between each of the plurality of first devices and the second device based on the propagation time of information or a signal between each of the plurality of first devices and the second device; A position specification step of specifying the position of the search target on which the second device is mounted based on the distances between each of the plurality of first devices and the second device calculated in the distance calculation step and the position information of the object to which the first device is attached or the attachment site of the first device; The search method is characterized by including the above steps.

7. A search method for specifying the position of a search target using a first device attached at arbitrary multiple locations and capable of acquiring its own position information and a second device attached to or associated with the search target, A distance calculation step of calculating the distance between each of the plurality of first devices and the second device based on the propagation time of information or a signal between each of the plurality of first devices and the second device; A position specification step of specifying the position of the search target on which the second device is mounted based on the distances between each of the plurality of first devices and the second device calculated in the distance calculation step and the position information of the first device acquired by the first device; The search method is characterized by including the above steps.

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